Vendeira P, Pignatelli D, Neves D, Magalhães M M, Magalhães M C, Vinson G P
Department of Histology and Embryology, Faculty of Medicine and IBMC, University of Porto, 4200 Porto, Portugal.
J Endocrinol. 1999 Jul;162(1):21-9. doi: 10.1677/joe.0.1620021.
Adrenocortical regeneration after adrenal autotransplantation provides a model for the study of local autocrine/paracrine mechanisms involved in the growth and differentiation of the adrenal cortex. To study the possible involvement of some growth factors, namely basic fibroblast growth factor (bFGF, FGF-2) and insulin-like growth factor I (IGF-I), in cell differentiation, immunohistochemical and ultrastructural studies were carried out on adrenal autotransplants in adult male rats. To distinguish between fasciculata and glomerulosa-like cells with accuracy, tissue sections were immunostained with IZAb, which recognizes the inner zone antigen (IZAg) present in fasciculata and reticularis cells but absent from the glomerulosa, and by electron microscopy. IGF-I-treated animals exhibited a clear glomerulosa-like zone that was devoid of IZAb immunostaining. In this outer subcapsular area, ultrastructural examination showed cells containing mitochondria with irregular cristae resembling those of the fetal or immature glomerulosa cells. In contrast, no significant morphological differences were observed in bFGF-treated animals when compared with those from saline-treated controls, in both of which, IZAb immunostaining occurred in almost all adrenocortical cells, with no clear zonation or glomerulosa, as seen in the intact animal. Plasma aldosterone and corticosterone concentrations were lower in autotransplanted control animals than in intact controls, although plasma renin activities were similar. IGF-I treatment significantly increased aldosterone concentrations, whereas corticosterone and plasma renin activity were reduced. bFGF infusion further reduced plasma aldosterone, although plasma renin activity and corticosterone were unaffected. These results suggest that the two growth factors have different effects on zonal differentiation and function in the autotransplanted gland. In particular, bFGF, by reducing glomerulosa function, appears partly to replicate the actions of ACTH in normal animals. In contrast, IGF-I enhances the glomerulosa secreting phenotype and diminishes that of the fasciculata/reticularis, possibly replicating the actions of angiotensin II or a low sodium diet.
肾上腺自体移植后的肾上腺皮质再生为研究参与肾上腺皮质生长和分化的局部自分泌/旁分泌机制提供了一个模型。为了研究某些生长因子，即碱性成纤维细胞生长因子（bFGF，FGF-2）和胰岛素样生长因子I（IGF-I）在细胞分化中的可能作用，对成年雄性大鼠的肾上腺自体移植进行了免疫组织化学和超微结构研究。为了准确区分束状带和球状带样细胞，组织切片用IZAb进行免疫染色，IZAb可识别存在于束状带和网状带细胞中但球状带中不存在的内区抗原（IZAg），并通过电子显微镜进行观察。用IGF-I处理的动物表现出一个清晰的球状带样区域，该区域没有IZAb免疫染色。在这个包膜下外侧区域，超微结构检查显示细胞内含有线粒体，其嵴不规则，类似于胎儿或未成熟球状带细胞的线粒体。相比之下，与生理盐水处理的对照组相比，bFGF处理的动物未观察到明显的形态学差异，在这两组动物中，几乎所有肾上腺皮质细胞都有IZAb免疫染色，没有完整动物中所见的清晰分区或球状带。自体移植对照组动物的血浆醛固酮和皮质酮浓度低于完整对照组，尽管血浆肾素活性相似。IGF-I处理显著增加了醛固酮浓度，而皮质酮和血浆肾素活性降低。bFGF输注进一步降低了血浆醛固酮，尽管血浆肾素活性和皮质酮未受影响。这些结果表明，这两种生长因子对自体移植腺体的区域分化和功能有不同的影响。特别是，bFGF通过降低球状带功能，似乎部分地复制了促肾上腺皮质激素在正常动物中的作用。相比之下，IGF-I增强了球状带的分泌表型，减弱了束状带/网状带的分泌表型，可能复制了血管紧张素II或低钠饮食的作用。
